Smoke abatement process

ABSTRACT

A PROCESS OF ELIMINATING NOXIOUS ELEMENTS FROM A CONFINED STREAM OF SMOKE BEFORE BEING DISCHARGED FROM AN OUTLET INTO THE ATMOSPHERE, INCLUDES INJECTING AN OXIDIZING AGENT AND A MONOHYDRIC ALCOHOL CONTAINING NOT MORE THAN FOUR CARBON ATOMS INTO THE CONFINED STREAM TO INSURE MIXTURE OF THE NOXIOUS ELEMENTS WITH THE OXIDIZING AGENTS AND   ALCOHOL, AND IGNITING SUCH MIXTURE TO CONSUME THE NOXIOUS ELEMENTS.

F 1971 RF. DE CASTRO 3,563,697

SMOKE ABATEMENT PROCESS Filed Oct. 13, 1969 2 Sheets-Sheet 1 PRESSURIZEDALCOHOL INVENTOR Raul F. de Castro ATTORNEYS Feb. 16, 1971 R. F. DECASTRO SMOKE ABATEMENT PROCESS 2 Sheets-Sheet 2 Filed Oct. 13, 1969 GASI INLET DUCT 40 FRESH AIR INLET DUCT SAMPLE POINT COMBUSTION CHAMBERDAMPER AIR PUMP INVENTOR. Raul F. de Cos'iro ATTORNEYS United StatesPatent 3,563,697 SMOKE ABATEMENT PROCESS Raul F. de Castro, Olean, N.Y.,assignor to R. F. de Castro Interprises, Inc., Olean, N.Y., acorporation of New York Continuation-impart of application Ser. No.558,018, June 16, 1966. This application Oct. 13, 1969, Ser.

Int. G1. now 53/34 US. Cl. 23-2 9 Claims ABSTRACT OF THE DISCLOSURE Thisapplication is a continuation-in-part of my copending application Ser.No. 558,018, entitled Method of Eliminating Noxious Elements From aStream of Smoke, filed June 16, 1966, and now abandoned.

This invention relates to improvements in smoke abatement processes, andmore particularly to a new and improved process or method ofeliminating, removing or abating noxious elements from a gaseousatmosphere, such as a confined stream of smoke before being dischargedthrough a conduit such as a flue, stack, chimney, or an automotiveexhaust pipe, preferably but not necessarily through an open end thereofinto the atmosphere. By smoke is meant the gaseous products ofcombustion or other physical and/or chemical reaction, whether or notmade visible by the noxious elements therein. By noxious elements ismeant those products of combustion or other physical and/or chemicalreaction which cause noxious air pollution to some degree and canproduce effects which are noticeably harmful to people, animal and plantlife, and which, while excluding certain products such as water, stableoxides and completely burned ash, include a wide variety of substances,whether in liquid, gaseous or solid form, whether normally visible orinvisible, and whether chemically referred to as elements or mixtures orcompounds thereof, such as carbon monoxide, oily particles, soot,incompletely burned ash, sulfur compounds, hydrocarbons, oxides ofnitrogen and the like.

A primary object is to provide a low cost process which reduces suchnoxious elements to an acceptable level by means which forms at leastpart of or can be readily installed in or on a conduit such as a chimneyor automotive exhaust pipe and operates reliably to effect admixture ofthe active ingredients with the noxious elements of the smoke, as wellas reaction therebetween, preferably by ignition and combustion thereof,to consume the noxious elements. Other objects are to provide suchmethod which does not substantially alter or change the normal course ofthe smoke as it travels through the conduit wherein the reaction occurs,does not impede the flow of the smoke by passing it through anymechanical structures, does not compress, force, or substantially changethe course of the smoke in any way, and does not use any solidcatalysts.

I have found that by introducing a monohydric alcohol, (ROH) preferablyone having not more than about four carbon atoms, such as ethyl ormethyl alcohol, be cause of cost, into a gaseous atmosphere, such as aconfined stream of smoke traveling in normal manner as by ice rising upthrough a chimney or stack type conduit toward the open top end thereof,along with an oxidizing agent in such a manner as to insure intimatemixture thereof and by causing a reaction between such noxious elements,alcohol and oxidizing agent, preferably by igniting such mixture, thenoxious elements of the smoke are consumed or reduced to an acceptablelevel before being discharged, preferably into the atmosphere, althougha closed receptacle could be used. The oxidizing agents which have beenfound adequate include hydrogen peroxide or pure oxygen propelled orinjected into the confined stream of smoke by means of compressed air,which also may be used by itself. I have found that such injectionproduces an effective mixture so that ignition thereof will effect thedesired elimination of noxious elements. Water can be used to slow downthe process, and the amount of water in the aqueous solution of alcohol,and hydrogen peroxide, if used, will have such a slowing down effect.Normally, not more than aqueous solution of alcohol would be used.

FIG. 1 is a diagrammatic representation of a chimney equipped withapparatus for carrying out my inventive process, particularly as appliedto abatement of smoke from a coal burning furnace.

FIG. 2 is a diagrammatic representation of another and more preferredapparatus for carrying out my inventive process, particularly as appliedto the abatement of smoke from a nitric acid plant.

Referring now. to FIG. 1, chimney 1 has a fine 2 leading from a furnaceduct 3 to an open upper end 4 through which the products of combustionare discharged into the atmosphere. At a distance down from the openupper end 4, preferably not less than about 3 feet or a workabledistance is an injector 5 comprising one or more nozzles for the liquidagents and one or more nozzles for the gaseous agents. As shown, theinjector has a nozzle 6 arranged to discharge an aqueous solution ofalcohol and a nozzle 8 arranged to discharge an aqueous solution ofhydrogen peroxide upwardly into the flue 2 at one side thereof. Thenozzle 6 can be supplied with ethyl or methyl alcohol via a line 9containing a valve 10 from a pressurized source 11 of such alcoholsolution. The nozzle 8 can be supplied with hydrogen peroxide via a line12 containing a valve 13 from a pressurized source 14 of such hydrogenperoxide solution. The gas nozzle 15 of the injector 5 is shown asarranged to discharge compressed gas against the outlet ends of nozzles6 and 8 so as to form the liquids issuing therefrom into a fine mist soas to condition the liquid for intimate mixture with the incompletelyburned solid and gaseous phases of the smoke. This nozzle 15 can besupplied with air via a line 16 containing a valve 18 from an airpressure source 19. Alternatively or concurrently, this nozzle 15 can besupplied with oxygen in purer form than in air via a line 20 containinga valve 21 from an oxygen pressure source 22. Obviously, the injector 5can take many forms and the particular agents used will depend on costand availability.

The apparatus also includes a pilot or ignitor shown as being in theform of a flame 25 from a burner 26 in the flue 2 above the injector 5.This bumer 26 can be supplied with gas, with or without air via a line28 containing a valve 29 from a pressurized gas source 30. Aconventional air mixer 31 can be used to supply the air necessary formaintaining the flame 25. Desirably the flame 25 is about twenty-fivefeet or a workable distance above the injector 5 and about 3 feet or aworkable distance below the open top 4 of the chimney so as to bothpermit proper mixture of the oxidizing agents and alcohol with theincompletely consumed constituents of the smoke, and also to insure thatthe flame 25 will not be blown out by atmospheric wind currents ordowndrafts.

In use, the smoke from the furnace duct 3 with incompletely consumedsolid and gaseous noxious phases or elements, such as carbon monoxide,oily particles, soot, incompletely oxidized sulfur compounds andincompletely oxidized fly ash, travels as a confined stream up the flue2 of the chimney 1. On passing the injector 5, the compressed air oroxygen from the nozzle 15 is directed against the nozzles 6 and 8 toforce the alcohol and any hydrogen peroxide issuing therefrom toward thecenter of the flue 2 as a fine mist which is quickly sorbed or occludedby the unburned or partly oxidized noxious components or elements of thesmoke. These components, so loaded with both alcohol and also loadedwith or being in the presence of one or more oxidizing agents thentravel into contact with the flame 25 as an intimate mixture. Immediateignition takes place, the alcohol combined with the reduced and partlyoxidized components of the smoke as well as with the oxidizing agent oragents, providing an intimate mixture which continues reduction andoxidation of the smoke components to such extent as to render themacceptable to be discharged into the air.

In actual practice, if the results are not adequate, more alcohol and/oroxidizing agents are used. If too much alcohol is used, the level ofactive combustion will lower to the injector 5, die out, and reignitewhen a fresh mixture reaches the pilot flame 25, this resulting in aneasily detectable pulsating combustion which the operator can correct byreducing the alcohol supplied. If too little alcohol is used, the smokewill bear a corresponding quantity of visible unburned particles. Thelevel of combustion is that which admixture of the alcohol, oxidizingagent and noxious elements is complete and will stay at the equilibriumlevel until a change occurs, such as increased draft, which will raisethe level.

In an actual installation where soft coal was used to generate 60 kw. ofelectricity from soft coal by means of a boiler and steam engine, themetal stack 1 was 47 feet high and had an inside diameter of about 18inches. The pilot flame 25 was 3 feet from the open top 4 of the chimneyand was served with butane gas. The injector was placed abouttwenty-five feet below the flame 25. Air from 19 and a small amount ofoxygen from 22 was used at about 60 p.s.i., the air constituting about90% of the gas discharged from across the top of the nozzle 6 from whicha to 50% aqueous ethyl alcohol solution was discharged, the supply line9 having a one-eighth inch inside diameter. At a cost of about $8.00 amonth, the smoke was rendered unobjectionable.

Turning to FIG. 2, the apparatus diagrammatically shown therein isparticularly adapted for use in carrying out the inventive process asapplied to removing the various noxious oxides of nitrogen from smokeemanating from a tail or flue gas stack of a nitric acid plant (notshown), and includes a flue gas inlet duct leading from such tail gasstack (not shown) and provided with a conventional sample extractingtube device 41 and an adjustable damper 42. The outlet end of duct 40 isconnected to a combustion chamber 43 supporting the lower end of a stackor flue 44 which is provided adjacent its upper end with another sampleextracting tube device 45 like device 41 in duct 40. Combustion chamber43 is supported on a hollow base or housing 46 which may or may not beportable, as desired, and through the upper end wall 46a of whichprojects a fresh air duct 48 opening at its upper end into combustionchamber 43 at about the level of the top of flue gas inlet duct 40.Adjacent its open lower end, which may be supported in any suitablemanner in housing 46, duct 48 is connected to the outlet duct 49 of anair pump 50 suitably supported on shelf 51 in housing 46 and providedwith a fresh air inlet duct 52 projecting through side wall 46b of thehousing and provided with a damper 53.

On the outside of the upper end of the opposite side wall 460 of housing46 is supported an alcohol fuel tank 54 connected by supply line 55having a shut off valve 56 and extending through wall 460 to the inletof fuel pump 58 suitably mounted on another shelf 59 in the housing. Theoutlet of pump 58 is provided with a fuel feed line 60 suitably passingupwardly through and secured in fresh air duct 48 and provided at itsupper end with an atomizing nozzle 61 located just above the open upperend of duct 48. A relief valve 62 is connected to lines 55 and 60 on theinlet and outlet sides of pump 58 by branch lines 55a and 60arespectively. The apparatus is completed by an ignitor generallyindicated at 63 and preferably of the electrical spark type, with thetwo electrodes 63a and 6311 being located closely above nozzle 61.

In carrying out the inventive process with the apparatus of FIG. 2,which is preferred over that of FIG. 1 because the mixture issufficiently intimate upon injection by reason of atomizer nozzle 61, soas to permit substantially instantaneous ignition, without significanttravel of the stream being required, the flue gas enters combustionchamber 43 through duct 40 and mixes with the fuel from atomizing nozzle61 and with fresh air from duct 48. This intimate mixture issubstantially immediately ignited by ignitor 63 and burned, with theabated products of combustion exiting up through stack 44 to theatmosphere. The alcohol from fuel tank 54 is pumped through lines 55 and60 to nozzle 61 by fuel pump 58, while fresh air from the atmosphere ispumped to combustion chamber 43 by air pump 50 through ducts 52, 4'9 and48. Damper 42 in duct 40 controls the flow rate of flue gas tocombustion chamber 43 and damper 53 in duct 52 controls the flow offresh air thereto, while relief valve 62 maintains constant fuelpressure to atomizing nozzle 61, all to ensure the desired intimatemixture of these fluidic components.

In an actual installation, the diameter of stack 44 Was six inches; thediameters of ducts 40 and 48 were about four inches each; the diameterof line 60 was about .25 inch; the overall length of stack 44 andcombustion chamber 43 was about 6 feet, and the ignitor 63 was spacedabout one inch above nozzle 61. The flow rate of the dark yellow smokeor flue gas from a nitric acid plant was approximately 200 cubic feetper minute at a temperature of about 700 R, an approximately 50% aqueousmethyl alcohol solution was introduced into combustion chamber 43 at arate of approximately one gallon per hour and fresh air at ambienttemperature was introduced to provide the oxidizing agent at a pressureof about 1 to 2 inches H 0 and at a flow rate of about 2 to 8 cubic feetper minute. The flue gas entering duct 40 was sampled by device 41, andupon anlysis, indicated approximately 3600 parts per million of noxiousoxides of nitrogen present, while the abated gas was sampled by device45, and upon analysis, indicated approximately 200 parts per million ofsuch oxides of nitrogen present therein. This represented approximatelya reduction in such noxious oxides of nitrogen; other similar testsresulted in almost 99% abatement of such nitrogen oxides, and in eachinstance a reading of zero was obtained on the Ringleman scale, (i.e.colorless smoke).

While the inventive process has been described and illustrated herein byreference to but two embodiments, this is to be taken as illustratingrather than as limiting the scope of the invention, which scope is to bedetermined by the appended claims. For example, either apparatus may beemployed for smoke abatement purposes generally, and they are notrestricted to the particular types of gaseous atmospheres described inconnection therewith. Also, the inventive process may be carried out byany other suitable apparatus, such as one installed in or forming atleast part of an automotive exhaust system.

What is claimed is:

1. A process of eliminating noxious elements from a gaseous atmospherecomprising introducing a monohydric alcohol (ROH) containing not morethan about four carbon atoms and an oxidizing agent into said atmospherein such a manner as to insure mixture of said noxious elements with saidalcohol and oxidizing agent, and causing a reaction between said noxiouselements, oxidizing agent and alcohol by igniting said mixture toconsume said noxious elements.

2. The process of claim 1 wherein said gaseous atmosphere is a confinedstream of smoke, said oxidizing agent and alcohol are introduced byinjection into said confined stream, and said reaction is caused byigniting said mixture before said confined stream is discharged from anoutlet.

3. The process of claim 1 wherein said alcohol is not more than about90% aqueous solution.

4. The process of claim 1 wherein said oxidizing agent includescompressed air.

5. The process of claim 4 wherein said oxidizing agent also includeshydrogen peroxide or oxygen or both.

6. The process of claim 1 wherein said gaseous atmosphere is a confinedstream of coal gas smoke, said alcohol and oxidizing agent areintroduced by injection into said confined stream, said reaction iscaused by igniting said mixture before said stream is discharged from anoutlet.

7. The process of claim 6 wherein said confined stream is permitted totravel toward said outlet a sufiicient distance to insure intimatemixture of said noxious elements with said alcohol and oxidizing agentbefore igniting the same, said alcohol is not more than about a aqueoussolution of ethyl alcohol, and said oxidizing agent includes compressedair and oxygen.

8. The process of claim 1 wherein said gaseous atmosphere is a confinedstream of flue gas smoke from a nitric acid source, said alcohol andoxidizing agent are introduced by injection into said confined stream,said reaction is caused by igniting said mixture before said stream isdischarged from an outlet.

*9. The process of claim 8 wherein said mixture is ignited substantiallyimmediately following said injection, said alcohol is not more thanabout a 50% aqueous solution of methyl alcohol, and said oxidizing agentis compressed arr.

References Cited UNITED STATES PATENTS 1,432,582 10/1922 Will 232773,232,713 2/1966 Felder 232X 3,248,178 4/1966 Hoskinson 232X EARL C.THOMAS, Primary Examiner US. Cl. X.R. 2s 4, 159, 277

